Apparatus for making transmission belts



p 1952 R. s. CARTER ET AL APPARATUS FOR MAKING TRANSMISSION BELTS 3 Sheets-Sheet 1 Original Filed Jan. 24, 1944 zlvwe/wto o RAYMOND s. CARTER. DECEASED 4 BY MARY H.CAI?TE1?,EXECUTQ|X AND MARVIN L. DORF P 23, 1952 R. s. CARTER ET AL APPARATUS FOR MAKING TRANSMISSION BELTS 5 Sheets-Sheet '2 Original Filed Jan. 24, 1944 RAYMOND S. CARTER, DECEASED BY MARY u. cmzmz, EX ECUTI2\X AND MAPVIN L. DORF mew;

Se t. 23, 1952 R. s. CARTER ET AL APPARATUS FOR MAKING TRANSMISSION BELTS 3 Sheets-Sheet 3 Original Filed Jan. 24, 1944 grwwwfw RAYMOND S. CARTER, DECEASED gun/A7 BY MARY H. CARTER, EXECUTRIX AND MARVIN L. DORF Patented Sept. 23, 1952 BELTS Raymond S. Carter, deceased, late o f Cuyahoga Falls, Ohio, by Mary H. Carter, executrix, Goyahoga Falls, Ohio, and Marvin L. Dorf, Lincoln, f

Nebr.,

assigncrs to Wingfoot Corporation,.

Akron, Ohio, a corporation of Delaware Original application January 24, 1944, Serial No. 519,448. Divided and this application November 12, 1948, Serial No. 59,442

Y 4 Claims. 1

This invention relates to an improved apparatus to produce power transmission belt of the endless type composed of fabric and rubber utilizing the improved method described and claimed in our United States Patent No. 2,456,580 issued December 14, 1948, of which this is a division.

For the purpose of illustrating and describing this invention, we choose a belt of trapezoidal cross-section generally referred to as a V-belt, but the invention is not limited thereto.

The apparatus employed by this invention to form and vulcanize belts is one in which the belts produced are of uniform cross-section throughout their length and will be free from wobble or other irregular motion and will retain their initial or natural stresses while running over two or more pulleys.

Previous methods of making belts of this character have been to build the various elements up one on top of the other on a cylindrical drum, slit the plied up cylinder into endless bands, covering said bands with one or more plies of fabric, placing in a mold, and vulcanizing. Other methods may vary somewhat but they all lead to a common and frequent occasion for rejection; that is, lack of uniformity due to unavoidable variations such as fabric gauges, rubber stock gauges, inequalities set u in pulling on'the cover and rolling same down, etc. Such inequalities are algebraically accumulative and, as a result of such methods, uniformity to a desired degree is impossibl to control and results in a high percentage of re-, jections involving a high labor cost and waste of material. This is particularly truewhen wire is used as a reinforcement. .Due to the unyielding nature of the wire, a maximum of accuracy is required in assembling the various elements of the belt body, otherwise, when the belt is placed in a mold for vulcanizing, the wires tend to buckle causing such irregularities that many belts are rendered unfit for use. Belts made by previous methods are vulcanized. in a circular mold and placed therein in the same position in which they are preliminarily formed, whereby all the elements are in neutral position. When belts made by these previous methods are placed over two or more pulleys, all elements of the belts are immediately put under stress. The bottom side of the belt in contact with the pulleys is in compression and the same portion extending between the pulleys is in tension. The top side of the belt over the pulleys will be. in tension, and the top portion between the pulleys will be in compression. Thus, the top and bottom areas of the belt. will be constantly flexing and alternatingf'rom tension to compression while running. 'This constant reversal of stresses generates fatigue and material- 1y shortens the useful life of such belts.

An object of this invention is to provide an apparatus that produces belts of uniform cross-section which Willrun true, will eliminate buckling of the reinforcing member whether composed of fiber cords or steel wire, will eliminate wobble or vibration while running, reduce heat, and .give longer and more efficient service than belts' made by former methods.

These and other advantages are accomplished by forming the top side or tension portion of the belt in the form of a fiat circularband which may be reinforced with either fiber cord or steel wire, placing the band over' a sectional ring, the band contacting surface of which forms the inner wall of a mold cavity, and thereafter formingthe bottom compression side of the belt by injectin the plastic stock under pressure into the remaining space of the mold, and 'vulcanizing the thus formed belt in an inside out position in thesam'e mold in which it is formed. Thusthe mold serves a dual purpose of a means for fOIIlliIlg and a' means for vulcanizing belts of this type. r

A belt formed and vulcanized in a circular mold cavity by this method results in the top and bottom sides of the belt being initially. in neutral position while in acircular inside-out position,

but when the belt is reversed to its normal operating position and held in a circular form, the bottom side of the belt will be in compression and the reinforced top side will be in tension. This is also true when a beltis placedovertwo or'more pulleys; all portions of thebottomor'cushion side. will remain in compression, and all portions of the top side will remain in tension, and these stresses remain the same whilethe belt is in operation. Thus no change results in any portion from tension to compression or from compression to tension. While running, the bottom side of the belt between pulleys will be in residual compression with respect to the portion encirclingthe pulleys, V

and the top area in tension.

A belt formed and vulcanized wrong side out according to this invention will prolong its useful life. Such a belt, which is composed largely of rubber, will endure much more flexing while under constant compression than when periodically and rapidly alternating from compression to tension. Such changes from compression to tension generate heat which induces a destructive influence in a belt of the conventional type thereby causing separation of the various elements. A,

further advantage of a belt made in accordance with this invention is that the reinforcing cords or wires in the top side of the belt will be consolidated in the finished product in the same undistorted relation in which assembled thus insuring desired uinformity of unit stress in service throughout its length. These and othe features and advantages will be apparent when considered in view of the following description and the accompanying drawings in which:

Fig. 1 is an elevation of a drum showing the reinforced element of the top side. of the belt assembled thereon, illustrating a so-called raw-edged type of belt;

Fig. 2 is an end view of Fig. 1;

Fig. 3 is the same as Fig.1 except the outer cov ering for the belts is shown as extended from the reinforced top side of the belt; illustrating a p f e t. he e n he es a en as d y e turn-up of the base cover;

Fig. 4 is an end view of Fig. 3;

Fig. 5 is a cross-sectional view of a segmental ring h a reinforc top por on of lbeit. in place thereon;

P 6 is e Plan view of .Fig. w h one. her eement removed i 'I s a cross-s ctional view of a mol wi h the segmental ring and top portion assembled therein;

a 8 s a c s-se tio al v ew howin a l with all the elements assembled therein, including the injection feed device as having introduced the plastic body mass within the mold cavity;

i 9 is a. fr me a y ross sectional view showing the plastic entering the mold cavity;

Fig. 10 is a fragmentary cross-sectional view showing he ne in hich the pla ic ba s;

Fig. ii is a plan view of the bottom half of a mold showing the. cavity partly filled;

Fig. 1 2 is a cross-sectional view showing a mold with all the elements therein; the plastic body mass of the belt having been fully injected;

13 is an elevation partly in section showing w e mold fi l may b expedi ed. by providing two filling orifices;

Fig. 14 is an elevation showing how two molds may be filled simultaneously by the same pressure unit;

Fig. 15 is a cross-sectional view of a belt void of side fabric;

Fig. 16 is a cross-sectional view of a belt having the sides and a portion of the bottom covered with fabric and Fig. 17 is .a cross-sectional view of a belt in which an outer envelopev is applied after forming.

The top side or tension member of belts of this characteris composed of one or more plies of rubberized fabric in combination with a longitudinally disposed strength reinforcing medium which may be either fiber cords or steel wire. The tension members are preferably built up on a cylindrical form 5 as illustrated in Figs. 1 and 2. In Fig. 1, two plies of fabric .6 are first applied to the cylindrical form or drum 5, after which reinforcing cord or wire 1 is wound upon the fabric plies 6 at predeterminedintervals whereby 4 the cords or wires are wound in close parallelism. After a predetermined number of revolutions, a space is skipped and the winding continued and so on all the way across the drum to form a plurality of such belt elements.

The windings are then preferably covered with one or more plies of rubberized fabric 8, the thus formed sleeve is then slit as at 9 into bands I0 which form the top side or tension portion of the belts, the width of the bands is determined by the size of the belt. The drum 5 is supported bythe bearings l4 and I5 and is driven by a sprocket wheel [6. The bearing I4 is conventionally and removably mounted to permit the bands ill to be removed endwise from the drum 5. The bands l8 illustrated in Fig. 3 are made in a similar manner as in Fig. 1, except that the distance between the reinforcing strength elements i1 is greater. This is to permit the rubberized fabric plies Hi to be turned up as shown at l9a. at each side of the reinforcing elements I! to form a fabric covering for the sides and the Whole or a portion of the bottom side of belts. This is desirable in certain types of belts.

After the reinforced tension bands In or l8 have been formed in the manner described, they r m v d from the drum and aned us s: m t l. ri 2 as. show i Fla. This n is. divided into four segments 24 25, 2 5 and'fl, which. p rm s a des red co t ol of he .e c im ferential d m nsi n i the s ep 91 mou tin the. reinforced fabric ban s I g or [8 thereon. in preparat on. for mo n ng a bend the is the e s. .4 end 5. re mo ed to ard. th center which pe m ts the se ments .6 end 2' to. b m ed. toward ne another. thus. perm t in the nds o be. easily plaoedobont hem- The m l r key segmen s 2 n 25 re th f rce into place, and. s. on a di i nal o d to x ed te. the mo i of the ha ds. a borti nei the o ter rface of the rin a e ed as at 211- .A se mental ring of this nature is of special importance because a band may be placed upon it without injury whereas, if. a. st h ur aced olid ing is used. h bon s may be sub ec ed to. nd e. t e s or rupture n o cin them in plane his i especia u wh n wi e is s d es. s e h 9ree= m B us a rin of this e. i ll e s le r h w r s icords to. booki he in er su of the ring is e se P o ide w t .e. pe ed su e 29. whic e nedi es Pos tionin the ring in a mold.

After a and is o ione he se men a ring 22, h rin with ha Pl e Posit oned in a ld .32 wh h. cons s s. o up e end ower in halves 3.3 and 3. as shown in Fi The o e 2. s provided ith e ee it in whieh belts ar form d and lcan zed eve se with e ec to their ,ao ol w r in p s tio e owe el ei g r ded w ten-ered su i ee 3E wh ch coinc s with the. in ertene ed sur a e 29 f the se menta r ng 1.2.- T hono belt is. s p ovided with a ta ered urioee 31 e oner ting wi t e outer tap r. 2. .o the. line A l. c e tend from. the mold cavi y o the pp s r c o the. m throu h whi h the nvul n zed robber mos i v i ec d t f rm the. under or c mp ess on s de. o bel s 3.9. se Pie .8.-. m trically opposi e the. ori .38 on ov fl w ve t 40 s p id d rou h. which mei e eone to enable th cavit to e. c mplete y and ev n y ed so tha elt w l be. uniform in densi y cross-sectional area. It will be noted that the ri ce is pa t a l f rme i th ow r vh i of the mold. as a 4.0. so tha the nj c e a e el vmold with the corresponding portion 82 in the upper half, dowel pins 43 are employed. The two halves of themold are locked together 'by conventional means 44.

After a mold is thus assembled with the segmental ring and reinforced band in place, the mold is placed in contact with an injection pressure unit 45 as shownin Fig. 8. The pressure unit is of conventional form and comprises a cylinder 46 in which operates a plunger 41 that may be operated by hydraulic pressure or other means. The bottom of the cylinder 46 is provided with an orifice 48 which registers with the orifice 38 in the mold, and when pressure is applied to the plunger 41 the plastic unvulcanized rubber 49 will beforced into the unfilled portion of the mold cavity 35 to completely and evenly fill said cavity and form the bottom or compression side of belts 39, Completion of the filling isindicated when the plastic 49 extrudes through the overflow vent to. The plastic material 49 passes through the orifice in the mold and into the mold cavity where it is forced both ways around the cavity as illustrated in Fig. 11.

The apparatus and procedure as described and illustrated in Fig. 8 is for the so-called raw edge belt or a belt having no outer covering offabric on its sides or bottom.

The apparatus and procedure for a belt formed as illustrated in Fig. 9 is the same as that shown and described for Fig. 8 except that in Fig. 9 the belt is provided with portions of fabric extending from each side of the reinforced bands I8 and integral therewith. These extending portions are for the purpose of forming a fabric covering for the sides of belts. The reinforced band [8, with the extending portions l8a is placed in a mold cavity, the extending portions having sufficient stifiness to enable them to maintain a position adjacent the mold cavity side walls. The plastic, material is injected with such force that the initial charge passes between the extending portions of fabric Ito and makes its first contact with the inner side of the mold cavity against the reinforced band l8 and begins to bank as indicated at 52 (Fig. 9). Said bank immediately begins to spread and progressively forces the extending portions of fabric 13a against the side portions of the mold cavity as shown in Fig. 10. The injection is continued until the plastic material extrudes through the vent 40 and the mold is completely filled, and the bottom or compression side 39 of the belt is formed as shown in Fig. 12. When formation of the belt is completed in the molds, the injection pressure cylinder is removed, the molds are then subjected to heat and pressure in the conventional manner, and the belt vulcanized therein. Thus it will be apparent that time and labor will be saved by using molds as a medium for both forming and vulcanizing belts in an inside-out position, and that a better and more satisfactory belt will result.

In order to expedite the filling of molds, it will prove to be advantageous, as illustrated in Fig. 13, to provide a pressure cylinder 54 having two extrusion openings 55 which coincide with corresponding openings 56 in the mold. By injecting the plastic rubber in this manner, the mold will be filled more quickly by permitting the plastic to flow more freely in both directions around the mold cavity.

A method in which two molds may be filled simultaneously is illustrated in Fig. 1A. This isaccomplished by placing the pressure cylinder 56 over two moldsfiland 58 in such amanner that the extrusionopenings 55 of thecylinder will register respectively withopenings 59-and 60. of molds when said molds areplaced close together and with the orifices 5i! and 60 positioned adjacent one another. I I

Fig. 15 illustrates abelt formed and. vulcanized in accordance with the foregoing description and is of the so-called raw e dg'ejtype, havingEno fabric" on the sides fthereofi "Fig.16 illustrates a belt having fabricjon' the sides thereof, andit I will be noted that the fabric covers the sides and turns the corners and extends a short distance on thebottom side of the belt.'

tion removed from the mold. One or more plies of fabric tl iare then placed 'overv the semiv'ulcanized form, placed in a second mold of slightly enlarged proportionawhich compensates for the added fabric plies, and subjected to a second vulcanization to complete the belt.

While certain representative. embodiments have beenshown for the purpose of illustrating the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

We claim:

1. A mold for forming and vulcanizing endles v-belts and the like comprising a bottom section having an upwardly extending portion with a frusto-conical surface; a segmental ring having a frusto-conical inner surface cooperating with the frusto-conical surface on said bottom section, the upper surface of said bottom section and said segmental ring being in horizontal alignment, the outer circumference of said segmental ring being provided with a vertical portion and tapered portion, said vertical portion forming a support for a portion of a belt; an upper section of said mold having an inner tapered surface embracing the outer tapered portion of said segmental ring in clamping relationship therewith, thereby forming in cooperation with said lower section and segmental ring, a cavity in which a belt may be formed; said mold having an orifice through which a vulcanizable material is injected under pressure into said cavity and an overflow vent diametrically opposite said orifice; and locking means to hold the mol members in sealing relationship. 2. A mold for forming and vulcanizing endless V-belts and the like comprising a bottom section having an upwardly extending portion; a segmental ring having means on an inner surface co-acting with means on the said upwardly extending portion of said bottom section to cause said segmental ring to expand as said bottom section and segmental ring are moved toward each other, a portion of the outer circumference of said segmental ring forming the-inner wall scram 7 belts and the like comprising a bottom section having an upwardly extendingv portion; a segmental ring having an inner surface cooperating with the surface of said upwardly extending portion of said bottom section, the outer circumference of said segmental ring, being provided with a vertical portion and a tapered portion, said vertical portion forming a support for a portion of the belt; an upper section or said mold having an innersurface embracingthe surface of said tapered portion .of said segmental ring in clamping relationship therewith, thereby forming in cooperation with said lower section and segmental ring a cavity iniwhich a beltmay be formed; and said" mold having an orifice through which a vulcanizable material may be injected.

4. A mold for forming and vulcanizing endless belts and the, like comprising a bottom section having an upwardly extending portion; a segmental ring having aninner surface cooperating with the surface of said upwardly extending portion of said bottom section, theouter circumference of said segmental ring being provided with a vertical portion and a tapered portion, said vertical portion providing a support for the tension member of said belt and forming the inner wall of the mold cavity; an upper'section of said mold having an inner surface embracing the surface of said tapered portion of said segmen- 8 t'al ring in clamping relationship therewith, thereby forming in cooperation with said lower section and segmental ring a cavity in which a belt may be formed; and said mold having an orifice through which a vulcanizable material may be injected. V

MARY H. CARTER, Ewecutriz 03 the Estate of Raymond S. Carter,

Deceased.

MARVIN L.- DORF.

REFERENCES CITED The following references are of record in the file of this patent:

' UNITED STATES PATENTS 

